Local Hazardous Weather Conditions

• The summer and winter seasons each have characteristic hazardous weather events. The Levante southeasterly winds create several, at least unpleasant, events each season while winter frontal passages occur frequently from late October through March.

• Levante wind events first develop over the western Mediterranean. An essential synoptic feature is higher pressure over the western Mediterranean/eastern Spain region, and lower pressure in the Gulf of Cadiz. The Levante evolution is influenced by a Venturi effect through the Strait of Gibraltar and establishment of a lee side thermal trough extending from the west coast of Morocco northward across the Gulf of Cadiz to Portugal. The Strait will generally experience funneled easterly winds from 20 to 55 kts prior to the onset of southeasterlies of 15 to 35 kt in the Rota area.

• Local indicators which may provide advance warning of the onset of a Levante include:
  • A late morning to afternoon offshore wind vice normal onshore sea breeze at the airfield. This wind anomaly often precedes a Levante by one day.

  • Local mariners use 'Levante Bugs' as a warning. A day before the Levante reaches Rota, a combination of bugs and insects ahead of the strong easterly winds may be observed.

  • Pressure differences between Palma(LEPA) and Casablanca(GMMC) can determine wind strength. If Palma minus Casablanca pressure is > 8 mb, > 40 kts winds in the Strait and Levante conditions in Rota.

• During winter the approach of frontal systems may be indicated by arrival of long period swell. Fast moving fronts approaching from the northwest may be preceded by westerly swell. Slower moving fronts associated with cyclonic development to the southwest of Rota are likely to be preceded by southwesterly swell. Cyclone development of this type may also be reflected by increased speeds of the prevailing easterly offshore winds.

• Any reversal of the prevailing summer onshore or winter offshore wind patterns are indicative of synoptic scale changes and likely foretell of approaching unsettled weather.

• Local forecasts and ample meteorological data are available from the Naval European Meteorology and Oceanography Center (NEMOC) . The Air Force 21st Operational Weather Squadron now provides weather suppport for Rota.